• Korean Journal of Microbiology
• /
• v.46 no.3
• /
• pp.308-312
• /
• 2010

Deinococcus geothermalis is a moderate thermophillic radiation resistant bacterium producing greater abundance of sugar metabolism enzymes than other Deinococcus species. In this study, optimal condition for xylanolytic activity of D. geothermalis was determined and xylooligosaccharides from oat spelt, beechwood, and birchwood xylan hydrolysates by this organism were analyzed through HPLC. Reducing sugar yield was increased in the order of beechwood, birchwood, and oat spelt xylan. D. geothermalis displayed maximal xylanolytic activity at $40^{\circ}C$ and pH 8.0. Magnesium ion increased xylanolytic activity upto 7.5 fold. Six kinds of xylooligosaccharides (xylose, xylobios, xylotriose, xylotetraose, xylopentaose, and xylohexalose) were detected from beechwood and birchwood xylan reaction products. Among them, xylose was the major product. However, only three kinds of xylooligosaccharides (xylose, xylopentaose, and xylohexalose) were clearly detected from oat spelt xylan. Gamma-ray (50 kGy) treatment of beechwood xylan, birchwood xylan and oat spelt xylan increased xylanolytic activity of D. geothermalis. The results indicate that D. geothermalis and pretreatment of radiation is useful for xylooligosaccharides production.

• Microbiology and Biotechnology Letters
• /
• v.44 no.3
• /
• pp.324-332
• /
• 2016

A bacterial strain capable of hydrolyzing xylan was isolated from fermented soybean paste obtained from a domestic Buddhist temple, using enrichment culture with rice straw as a carbon source. The isolate, named YB-1301, was identified as Bacillus safensis on the basis of its DNA gyrase subunit B gene (gyrB) sequence. The xylanase productivity of strain YB-1301 was drastically increased when it was grown in the presence of wheat bran or various xylans. In particular, the maximum xylanase productivity reached above 340 U/ml in the culture filtrate from LB broth supplemented with only birchwood xylan at shake-flask level. The xylanase production was significantly induced by xylans at the stationary growth phase in LB medium containing xylan, whereas only a small amount of xylanase was constitutively produced from cells grown in LB medium with no addition of xylan. Furthermore, xylanase biosynthesis was induced more rapidly by the enzymatically hydrolyzed products of xylan than by the non-hydrolyzed xylan. In addition, the xylanase in the culture filtrate of B. safensis YB-1301 was found to have optimal activity at 55℃ and pH 6.5–7.0.

• Journal of Microbiology and Biotechnology
• /
• v.6 no.3
• /
• pp.173-178
• /
• 1996

Synergic effects among endo-xylanase, $\beta$-xylosidase, and acetyl xylan esterase of Bacillus stearothermophilus in the hydrolysis of xylan were studied by using birchwood, oat spelt, and acetylated xylan as substrates. Synergism between endo-xylanase and $\beta$-xylosidase was observed on all three substrates tested, indicating that $\beta$-xylosidase enhanced the production of xylose by relieving the end-product inhibition upon endo-xylanase conferred by xylooligomers. Endo-xylanase and $\beta$-xylosidase also showed synergism with acetyl xylan esterase in the hydrolysis of birchwood and acetylated xylan, while no synergic effect was detected in oat spelt xylan hydrolysis. Thus, the hydrolysis of xylan containing acetic acid side chains required the action of acetyl xylan esterase, which eliminated the steric hindrance of the side chains, leading to the better hydrolysis by endo-xylanase and $\beta$-xylosidase , and the acetyl xylan esterase activity was also enhanced by endo-xylanase and $\beta$-xylosidase for the latter enzymes provided acetyl xylan esterase with shorter xylan oligomers, the better substrate for the enzyme.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.42 no.2
• /
• pp.1-11
• /
• 2010

The possibility of applying birchwood xylan in papermaking process to improve dry strength of paper was investigated. Unmodified xylan barely adsorbed onto pulp fibers while cationically modified xylan adsorbed substantially. Adsorption of cationically modified xylan by quaternarization with 3-chloro-2-hydroxypropy trimethylammonium chloride improved dry strength of paper. Chemical structure and degree of substitution of the cationically modified xylan was determined by 400 MHz 13CNMR spectroscopy and elemental analyzer. The amount of adsorbed xylan on cellulose fibers was greater when the cationicity was moderate, and it was interpreted that the conformation of this cationic xylan adsorbed on fiber surface was more favorable for greater adsorption due to its greater loop formation tendency while highly cationic xylan tends to adsorbed in stretched conformation. The physical properties of handsheets increased as the amount of adsorbed cationic xylan increased. On the other hands, the optical properties decreased with xylan adsorption.

• Journal of the Korean Wood Science and Technology
• /
• v.28 no.3
• /
• pp.25-33
• /
• 2000

This study was carried out to find the optimal isolation conditions of xylan from steam-exploded materials, such as rice straw(Oryza sativa), barley straw(Hordeum vulgare) and oak wood(Quercus mongolica), In the chemical composition, we found that the contents of water-extractives and ash of rice straw and barley straw were more than those of oak wood. Rice straw, barley straw and oak wood were steam-exploded at 20kgf/$cm^2$ for 3 minutes or 6 minutes. The content of lignin in three different steam-exploded materials was higher than that of non-treated materials. The crude xylan was extracted with hot water and 0.5% KOH solution from steam-exploded materials. In the sugar type of crude xylan extracted with hot water and 0.5% KOH solution, the oligomer content of crude xylan extracted with hot water was much more than that of crude xylan extracted with 0.5% KOH solution. The crude xylan was purified with 5% barium hydroxide Solution and ethanol precipitation procedure. The content of xylose of purified xylan was over 85%, but other sugar residues(arabinose, mannose, galactose and glucose) were not removed completely.

• Microbiology and Biotechnology Letters
• /
• v.11 no.1
• /
• pp.23-32
• /
• 1983

In the present study, two kinds of D-xylanases (1, 4-$\beta$-D-xylan xylanohydrolase (EC 3.2.1.8) were purified and characterized from crude extract of Aspergillus niger KG79. Xylanase I was most active at pH 5.0, whereas xylanse II at pH 4.0 Both enzymes demonstrated their maximum activity at 45$^{\circ}C$. They were relatively stable between pH 4.0 and 6.0 at 3$0^{\circ}C$ for 6 hours. Molecular weight of xylanse I and II were 12, 500 and 11, 500, respectively. Michaelis-Menten constants of xylanse I and II were 0.28% and 0.26% of xylan, respectively. Both enzymes could degrade commercial D-xylan to xylose, xylobiose, and xylotriose to the degree of about 10% of total reducing power. Xylanse I could, however, liberate arabinose from barley straw xylan in addition to xylose and xylooligasaccharides more rapidly than xylanase II. The degree of hydrolysis was about 25%. The reconstituted D-xylanase system with purified xylanases and $\beta$-xylosidase degraded commercial xylan and barley straw xylan to the degree of 28% and 54% respectively. The limit of hydrolysis by the enzymes was suggested to be resulted from the physical structure of the substrate.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.40 no.4
• /
• pp.43-50
• /
• 2008

Adsorption of xylans extracted from birchwood and oat spelt on Hw-BKP were analyzed using HPLC. The effect of xylan adsorption on paper properties such as tensile, tear index and brightness was also investigated. The constituents of xylan was analyzed with HPLC after hydrolysis with dilute sulfuric acid. It was shown that xylose was the major constituent and small amounts of glucose and galactose were contained in the xylan samples. Adsorption of xylan on hardwood fibers was evaluated using acid hydrolysis and HPLC techniques. Results showed that the adsorption of negatively charged xylan on the fiber surface was negligible probably because electrostatic repulsion between these two materials. Pretreatment of the fiber with alum increased xylan adsorption. The amount of adsorption increased up to 30 mg/g. With the increase of xylan adsorption both tensile and tear strength of the handsheet increased suggesting xylan can be a very effective strength agents for papermaking. Brightness of the handsheets decreased, however, with the use of xylan.

• Journal of Korean Society of Forest Science
• /
• v.35 no.1
• /
• pp.24-32
• /
• 1977

According to the chlorous salt method, most of holocellulose whose lignin was removed, was obtained. In extracting xylan from holocellulose by the different densities of alkali, 5% KOH was extracted three times but still there remained part of xylan in it and another composite of hemicellulose and cellulose was obtained. The extraction of 10% and 20% KOH showed a desirable result. Rather than the ordinary method to use a large quantity of ethanol in the precipitation isolation of xylan, the method to use a small quantity of ethanol in adopting the dialysis with cellophane-membrane by condensing density to one tenth, made il possible to extract a high purity xylan in a high retrieving rate. In isolating glucomannan, the residue of 5% KOH extraction contained a large quantity of xylan, the residue of 10% and 24% KOH extraction, also showed the same result and the comparison between glucose and mannose was approximately 1 : 1. The purification of Fehling solution made it possible to obtain comparatively pure xylan but the process of oxidation dissolution was complicated and the retrieving rate was low. This was not a good method. The ethanol titration purified a high purity xylan in a high retrieving rate and was a very excellent purifying method, considering its simple and easy process. These two purifying methods, however, could not completely remove the residue of arabinose. This will be examined and reported later.

• Microbiology and Biotechnology Letters
• /
• v.36 no.4
• /
• pp.307-313
• /
• 2008

The yeast surface expression system, pCTXYN (6.8 kb), of Bacillus endoxylanase gene (xynB, 642 bp) was constructed and introduced into Saccharomyces cerevisiae EBY100 cell. The transformed yeast cell showing the highest endoxylanase activity was selected through the active staining of colonies grown on YPDG medium containing xylan. With the yeast transformant, EBY100/pCTXYN, grown on galactose containing medium, it was found that the endoxylanase was successfully displayed on the yeast cell surface and the xylooligosaccharides were efficiently produced from xylan. The most of endoxylanase activity was detected in the cell fraction and reached about 1.9 unit/mL after 48 h cultivation. The optimized conditions for xylooligosaccharides production from xylan were determined as follows: substrate and its concentration, oat spelt xylan 6%; concentration of yeast whole-cell, 5 unit/mL; temperature, $50^{\circ}C$, and reaction time $2{\sim}4\;h$. When the oat spelts xylan and corncob xylan were hydrolyzed by treatment with cell surface-displayed endoxylanase, xylotriose was formed as a main product.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.21 no.4
• /
• pp.423-427
• /
• 1992

During the cultivation of Penicillium verruculosum in the medium containing xylan as a sole carbon source for 26 days, xylanolytic activity and some changes were investigated. Protein content and xylanolytic activity, p-Nitrophenyl-$\beta$-D-xylopyranoside (PNPX), p-Nitrophenyl-$\beta$ -D-glucopyranoside (PNPG) hydrolytic activities were increased until 8 days but reducing sugar content was not correlated to protein content. When crude proteins from the culture broth were separated on SDS-PAGE, distribution of proteins was different from the culture broth of cellobiose octaacetate (COA) medium. The culture broth of xylan medium had high hydrolytic activity on xylan but not on cellulose. Furthermore, xylanolytic products were showed xylose, xylobiose and oligosaccharides on thin layer chromatography, and xylobiose was major product. Those result suggested that xylanolytic activity of culture broth was endo-type hydrolysis. Optimum temperatures of xylanolytic activity and PNPX hydrolytic activity of culture broth were 50~6$0^{\circ}C$ and 60~7$0^{\circ}C$, respectively and optimum pHs were 3.0~4.0 and 4.0~5.0, respectively.